Abstract: An apparatus for measuring the temperature of liquid in a tank is disclosed. This apparatus comprises a plurality of temperature sensors spaced apart so that each temperature sensor senses the temperature of a predetermined volume fraction of the liquid in the tank; and a data processor associated with the temperature sensors and acting to process the temperature determined by each of the sensors to determine the volume weighted average temperature of the liquid in the tank.

Abstract: An apparatus useful for detecting a leak in a tank filled with liquid comprising:a measuring chamber adapted to hold a volume of liquid and having first sensing acting to monitor the volume of liquid in the measuring chamber;a level control chamber in fluid communication with the measuring chamber and the tank, and adapted to maintain a substantially constant liquid head on the tank, the level control chamber including inlet adapted to receive liquid from the measuring chamber to maintain the substantially constant liquid head and outlet adapted so that liquid flows from the level control chamber; anda catch chamber in fluid communication with the level control chamber and adapted to receive the liquid from the outlet, the catch chamber having second sensing acting to monitor the volume of liquid in the catch chamber.